Answer
$49x^2+70xy+25y^2$
Work Step by Step
RECALL:
$(a+b)^2=a^2+2ab+b^2$
Use the formula above with $a=7x$ and $b=5y$ to obtain:
$=(7x)^2+2(7x)(5y) + (5y)^2
\\=49x^2+70xy+25y^2$
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